<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>margin1</title>
        <style type="text/css">
            .outer{
                background-color: #1E9FFF;
                margin: 100px;
                overflow: hidden;
            }
            .inner{
                background-color: #FFFF00;
                margin: 50px;
                height: 50px;
            }
        </style>
    </head>
    <body>
        <div class="outer">
            <div class="inner"></div>
        </div>
    </body>
</html>